Monkeys infect bushmeat hunters

The transfer of viruses from animals such as monkeys to human populations is a relatively common event, suggests a study of African hunters.

A survey of a group of 1,000 bushmeat hunters in Cameroon has turned up two viruses that the researchers suspect come from primates. The result should remind us to stay on guard against diseases that spread from one species to another, say the researchers.

"These are not rare historical events. This is an ongoing phenomenon," says Nathan Wolfe, a field virologist at Johns Hopkins Bloomberg School of Public Health in Baltimore, Maryland, who led the study.

HIV, the virus that causes AIDS, is thought to have migrated from primates to humans. Ebola, an often fatal fever, is also thought to have entered the human population from primates in Africa. And last year, Wolfe and colleagues showed that a fairly innocuous bug called simian foamy virus had made the leap to hunters in Cameroon.

“Wherever you go in the world, people hunt local animals.”

Nathan WolfeJohns Hopkins Bloomberg School of Public Health

Now a survey of those same hunters has turned up two more viruses, the researchers report in the Proceedings of the National Academy of Sciences1. The viruses, called HTLV-3 and HTLV-4, are from a group known as the human T-lymphotropic viruses. Such viruses infect many millions worldwide, causing neurological disease in a small percentage of cases.

HTLV-3 and HTLV-4 have never been seen in humans before. HTLV-3 has a primate analogue and although HTLV-4 does not, the researchers strongly suspect that it originated in primates too.

Hunter network

Wolfe's team chose to study hunters in southern Cameroon because they are known to hunt and eat many different types of primates, as well as keeping them as pets. The man whose blood turned up the mysterious HTLV-4, for example, is a 48-year-old who has hunted monkeys, chimpanzees and gorillas.

The researchers, including scientists from the Army Health Research Center in Yaounde, Cameroon, are continuing their survey of the population. They say they hope to catch viruses in the act of leaping species.

Wolfe is also working on creating a network of hunters to help collect data. He says the best way to stem the spread of disease is to educate these hunters, and to give them incentives to hunt or raise different types of animal.

He hopes his work will also help to educate others about how and why primates are hunted in the first place, given that the activity often incites feelings of disgust in the Western world. "This shouldn't be portrayed as some dark and evil phenomenon that is happening in deepest Africa. Wherever you go in the world, people hunt local animals," he says.